Air Pump

What is an AIR Pump and where is it Located?

The AIR pump (Air Injection Reactor pump), also commonly known as a smog pump, is a type of secondary air injection system, and a critical part of a vehicle’s emission reduction system. The AIR pump is designed to pump in clean air and combine it with your engine's hot exhaust gas as it leaves the combustion chambers. It injects fresh, pressurized oxygen into the exhaust stream, usually at the exhaust valves or the exhaust manifold. This is necessary because combustion in the engine is never perfectly efficient, and hydrocarbons, like your fuel, need air to burn. The hot exhaust gas by itself is not enough to complete the burning of the exhausted gas mixture. The air pumped into the exhaust stream allows for the continued combustion of unburned fuel as it travels through the exhaust system and ultimately out of the vehicle via the tailpipe. Burned fuel is better for the environment than unburned fuel is, so the result of secondary air injection is the emission of cleaner exhaust gases.

Secondary air injection was introduced as a vehicle emissions control strategy way back in 1966, and in turn, AIR pumps were introduced as well. So you may also hear an AIR pump referred to as a secondary AIR pump or air injection pump. You may be asking “why the secondary designation, though?” The primary source of air is the engine of course, and that is where the exhaust system scavenges the exhaust (dirty air) from. It is also not the primary emission control on an automobile either, though on vehicles in the late 1960’s and early 1970’s, it was.

As emission control strategies evolved over time and became more effective, and the catalytic converter was introduced, the amount of unburned and partially burned fuel existing in the exhaust stream lessened. This changed the purpose of the secondary air injection system. The system was thus adapted to support the proper function of the catalytic converter, now the primary device for emission control, most important during a vehicle’s warm-up. So, when the engine is cold, the air that is injected at the upstream (original) point of injection cleans up the rich air-to-fuel mixture needed to start the engine. This raises the temperature of the exhaust, quickly bringing up the temperature of the catalytic converter to the point needed for it to operate, and so the secondary air system shuts down. On some larger vehicles, like trucks and SUVs, the secondary air system also pumps air into the exhaust manifolds during warm-up, and that air is then directed downstream to the catalytic converter itself while it is in operation in order to help burn off the large amount of fuel needed to run these types of large vehicles.

So, back to the AIR pump - how does it work exactly? The AIR pump is a type of rotary pump called a vane pump. When the pump is engaged, pressurized air is forced into the injection point(s) by the spinning vanes of the pump. The pump assembly includes a screen in order to filter out any large particles possibly contained within the air that could damage the system. A valve is present to prevent any backfire of exhaust through the air injection system, as this could damage the smog pump and other exhaust system components. There are two ways that the actual AIR pump motor itself can be powered. Mechanical pumps are driven by the serpentine belt and are usually found mounted on the engine. More modern electric pumps are driven by an electric motor receiving DC power from the battery and are also located under the hood. 

How do I Know if my AIR Pump Needs to be Replaced?

Since the smog pump is designed to help clean up your vehicle’s emissions, a failing pump can lead you to fail an emissions inspection, but hopefully it won’t come to that. If the pump isn’t working, it might cause your check engine light to come on. You may also notice the engine idling roughly or not having a good power output. Unburned fuel in the exhaust can cause your oxygen sensor to (incorrectly) determine that the fuel-air mixture is too rich, and consequently the engine control module will reduce fuel flow to the engine. If you have extremely keen ears, it may be possible to hear whether or not the pump is running. Those of you without super-hearing, though, may want to remove the pump and bench test it to see if it works. As always, consult your vehicle's repair manual and follow all precautions when performing any type of diagnosis.

Sometimes the secondary air injection pump can fail due to problems with the electrical motor as well. Many motors, due to frequent exposure to cold or wet weather, will corrode and freeze up on the inside, causing the smog pump assembly to malfunction. The internal parts of the AIR pump may also just simply wear out over time. 

Can I Replace an AIR Pump Myself?

Replacing the AIR pump will be achievable with some effort. Depending on your model and the exact location of the AIR pump, you may be able to access it in the engine compartment, or you may have to raise and secure the vehicle to access the part from below. You will need to disconnect the smog pump from its associated hoses and wiring, unbolt it, and connect the new one. 

Need a AIR Pump Replacement?

The smog pump is a critical piece of equipment that needs to be working properly in order to maintain proper emissions readings. Remember, a properly working AIR pump assembly results in reduced emissions of nitrogen oxides (NOx), not to mention increased gas mileage. Also, operating your vehicle on a public road with disabled emission equipment could violate the law. So, whether your car or truck needs a new mechanical or electric AIR pump or you are performing preventative maintenance, 1A Auto has you covered. We carry a large selection of replacement smog pumps, including both mechanical and electric, for many makes and models, and at great prices. Our AIR pump motors are built to strict quality control standards, made to the same specifications as the originals, and will fit and function with no hassle. They come with everything needed to change out the old motor, and make a great replacement for your old pump.

At 1A Auto, we also make shopping for a replacement AIR pump for your car, truck, SUV or van easy - we're here to help you select the right part for your vehicle! Call our customer service toll free at 888-844-3393 if you have any questions about our smog pumps, warranty, compatibility or to purchase, or you can buy online.